Spectral CT uses a single-source, multilayer detector that creates a conventional CT image. Dr TBS Buxi, Chairman CT & MRI Departments,Sir Ganga Ram Hospital

Conventional CT scans often produce ambiguous or inaccurate data that can require additional testing. To provide better patient experiences and empower you to improve clinical outcomes while achieving the economic objectives of your organization, there is a clear advantage in making the right the diagnosis as to be ensured in the first scan.

Computed tomography (CT) has enjoyed a prominent role in medical imaging since its creation in the 70s. This scanning modality provides a more complete picture of the body than conventional X-rays, its predecessor, taking images at several different angles to build a cross-section, including bone and tissue. The trouble is that it can be difficult to distinguish one object from another in the black-and-white background particularly when it comes to smaller lesions or metal artifacts within the body.

The CT scanner has evolved through the advancements in spectral imaging, the next phase of CT's evolution. By acquiring images at two different energy levels, the technique is able to differentiate the various elements in the body based on their material density or atomic numbers. The differences are displayed as varying shades of gray or even colors on the final image.

The spectral CT uses a single-source, multilayer detector that creates a conventional CT image. But the spectral, dual energy information is available in the background for use in post-processing. From a single scan, images can be viewed at different energy levels. Spectral information also can be viewed through an on-screen window Philips calls the Spectral Magic Glass that can be moved around the image; this ultimately helps streamline the workflow for the clinician.

Within cardiac imaging, clinicians are interested in the assessment of coronary artery disease (CAD) and its impact on function. In addition, cardiac CT is also used for the assessment of coronary stents for in-stent re-stenosis, and for planning of complex cardiac interventional procedures such as transcatheter aortic valve implantation (TAVI).

With spectral capabilities, along with a fast rotation speed (0.27 sec, standard temporal resolution of 135 ms in step and shoot cardiac with added improvements via adaptive multi-cycle reconstruction in helical), the spectral CT espiQoNis is ideally suited to address cardiac imaging challenges. Spectral reconstructions, which include (but are not limited to) mono-energetic (MonoE) and iodine no water, are always available either prospectively or retrospectively along with the standard conventional reconstructions.

In contrast to conventional reconstructions, which represent polychromatic X-ray, MonoE reconstructions (also Hounsfield Unit [HU]-based) show attenuation as if a single monochromatic energy (keV) was used to scan. These reconstructions can be displayed in real time, representing 161 different single energy levels between 40 and 200 keV. These MonoE reconstructions have multiple applications such as boosting of iodine signal (lower MonoE), improvement of contrast-to-noise ratio (CNR) (again lower MonoE), and reduction in calcium blooming, beam hardening, and metal artifact (higher MonoE).

Every pixel displayed in reconstruction represents components that behave like iodine and water.

Unlike MonoE, which is a HU-based image, iodine no water is a material density image that represents the iodine component with the water component suppressed. The iodine content is shown within a region of interest and reported in mg/ml. In general, while iodine no water is typically used to show iodine uptake, it has also been shown to enable assessment of the coronary arteries in the vicinity of calcium, while at the same time maintaining the contrast enhancement in the lumen.

Spectral CT has proven particularly helpful in vascular applications, with the ability to quantify arterial plaque in contrast-enhanced vessels. In a traditional black-and-white CT image, it can be difficult if not impossible to differentiate between iodine and calcium in the artery; spectral imaging via IQon displays the materials as two distinct colors. And you can fine-tune for iodine contrast on the spot, in a case where you might be dealing with a suboptimal CTA [computed tomography angiography], this could essentially make something which is non-diagnostic diagnostic. It should also be noted the system can maximize low contrast doses, getting a clear picture with as few as 20 cc.

The system is also drawing strong interest from oncology, with the ability to create an iodine map overlay, the viewer can see color-coded pixel-by-pixel density, allowing greater delineation of a tumor.

Spectral Diagnostic Suite on IQon CT is a suite of advanced visualization applications for the Philips IQon Spectral CT, the Spectral Diagnostic Suite delivers advanced spectral and clinical application tools, including Spectral Magic Glass
and the Spectral Magic Glass on PACS app.

The spectral CT and the spectral diagnostic suite easily and fully integrates into your current workflow, allowing you to acquire spectral results as part of a routine CT scan; review and analyze spectral data on PACS, with results ready in 5 minutes, integrate spectral solutions easily, because spectral is always on, 24/7; use spectral data to address a wide variety of complex clinical questions, and analyze spectral results retrospectively from anywhere within your enterprise.

The spectral CT machine is loaded with lot of unique clinical applications, which makes visualization easier and more powerful.

Spectral Magic Glass. In addition to conventional CT images enables on-demand simultaneous viewing and quick comparison of up to five different spectral results for a region of interest, including monoenergetic, iodine density, virtual noncontrast, iodine no water, and Z effective maps.

Spectral Magic Glass on PACS app. It conveniently launches directly in the user's PACS viewing setup. Spectral Magic Glass on PACS is only available with the IQon Spectral CT and offers a simple interface that integrates into your organization's current workflow with little or no training.

Low-dose solutions delivering on quality measure. With the spectral CT, you will have the full use of dose management tools – like iterative model reconstruction (IMR) and 3D dose modulation – allowing you to experience all the benefits of spectral data at the same dose levels as a conventional CT scan

Radiation dose management has come up as a major issue in radiological diagnosis, and Philips IQon has DoseWise Solutions, dedicated to controlling and managing radiation dose. At the center of the business is its DoseWise Portal software for dose tracking. The software includes a DoseAware personal dose monitoring system that measures and displays an individual's exposure to radiation in real-time. In addition, DoseAwareXtend makes real-time dose measurement even more precise and useful in a single display, giving immediate feedback on scattered X-ray dose per procedure to help staff manage exposure. DoseWise Portal is unique in that it simultaneously integrates dose tracking of both patients and staff, showing all the scanning protocols that are being used and their radiation dose burden. It includes a dashboard for tracking dose from different scans, and it enables users to set their own dose reference levels (DRLs) for following dose over time.

The spectral CT adds spectral resolution to traditional CT scanning through a new dual-layer spectral detector. With a yttrium-based scintillator, the NanoPanel prism detector identifies photons of high energy and low energy simultaneously, allowing you to not only view anatomy, but also use color to characterize the material content of critical structures.

I hope that in the future CT scanning would be significantly more powerful powered by these newer clinical applications and technologies and will continue to empower radiologists in delivering first time right diagnosis seamlessly.

10 Diagnostic Imaging Trends for 2018



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